DESCRIPTION: Complex assemblies are ubiquitous in nature and in materials science. DNA, microtubules, and cell membranes are but a few biological assemblies that owe their structural integrity to noncovalent interactions. Liquid crystals, monolayers and nanotubes are some types of materials that are likewise structurally well-defined. Organic chemists are in hot pursuit of ways to design, synthesize, and characterize new assemblies of such high structural complexity, with the hope that the new assemblies will be as useful as they are complex. Potential uses include transport devices, separation devices, switches, catalysts, and sensors. The general aim of this proposal is to create complex assemblies using organic modules, linking them either covalently (permanently) or noncovalently (reversibly) in well-defined manners. The assemblies will contain small molecules, encapsulated within and holding together the assemblies. Characterization of these assemblies will provide a contribution to the general understanding of the role of weak noncovalent interactions in molecular recognition and in the assembly process to form materials and biological assemblies. Various applications (vide infra) will be explored. Any contribution to the understanding of noncovalent interactions and how they relate to assembly processes would be invaluable to biomedical research. The interactions that are examined in this proposal are the same as those involved in the inhibition of enzyme activity, the antagonistic blocking of cell receptors, the intercalation of drugs with DNA, the bundling of microtubules, the organization of cell membranes, etc. In addition, there are potential applications that are directly relevant to health research, including transport of large guest molecules (these could be drugs) through membranes, tissue-specific drug-delivery devices, catalysis of biologically relevant reactions, and the detection and/or removal of toxins.